Semiconductor device packages are known and available in different sizes and configurations to address issues of, for example, power dissipation and operating frequency. Ceramic packages are known but the thermal resistance through these types of packages is often too high to conduct heat dissipated by the device in a sufficient manner to avoid excessive temperature rise and a subsequent decrease in the reliability of the semiconductor device. In a conventional ceramic package, a ceramic base is provided having a conductive area on the inside base surface on which a semiconductor device is mounted and having vias therethrough that contact a heat sink on the outer bottom of the base. The thermal paths are provided through the vias and through the ceramic base material itself.
Mounting the semiconductor device directly to the lead frame provides a low thermal resistance path to remove heat dissipated by the device from the package. Direct mounting of a semiconductor on a lead frame is known in injection molded plastic packages. In such plastic packages, however, the plastic completely fills the space surrounding the semiconductor device. For high frequency applications, the electromagnetic characteristics of the plastic typically detune and degrade the performance of the device embedded in the plastic. In addition, some semiconductor devices have delicate structures on the surface that can be destroyed during the molding process.
What is needed is a semiconductor package that allows high power and high frequency semiconductor devices to operate effectively.